A summer outbreak of whirlwind phenomena from Dublin bay to the Shannon estuary

Abstract

The conditions giving rise to a series of whirlwind phenomena that occurred across Ireland on 16–17 August 2001 are examined. Surface and upper air data, together with indices derived from upper air soundings (CAPE and LIFT) are used to analyse the roles of wind shear, instability and vertical moisture boundaries. While these showed some moderate wind shear, the potential instability was quite weak and vertical moisture contrasts were not strong. Despite this, one tornado, up to three waterspouts, two funnel clouds and an eddy whirlwind were reported over little more than a twenty four hour period. It is demonstrated that the most significant condition associated with their formation was probably vertical wind shear, in a weakly unstable, moist atmosphere.

Key index words:

• whirlwinds
• tornado
• waterspouts
• Dublin
• Shannon